1. Field of the Invention
This invention relates to ball-point pens and other writing instruments, containing a writing cartridge which is projected to operative position and retracted to inoperative position.
2. Description of the Prior Art
The following U.S. Pat. Nos. constitute the closest prior art known to applicant: 2,809,609 Clary, et al. October 15, 1957 2,881,736 Zepelovitch April 14, 1959 2,988,055 Platt June 13, 1961 3,071,112 Lovejoy, et al. January 1, 1963 3,130,710 Hansen, et al. April 28, 1964 3,203,402 Lockwood August 31, 1965 3,288,114 Ritter November 29, 1966
The closest of these patents is believed to be Zepelovitch U.S. Pat. No. 2,881,736. However, this patent does not appear to provide a projection-retraction mechanism which securely locks the writing cartridge in projected operative position. The extent of projection is inadequate. Moreover, the patent does not provide a smoothly, easily operable projection-retraction mechanism. And finally, the Zepelovitch patent does not provide a relatively inexpensive construction.